Dental casting ring



Patented Sept. 7, 1926.

JOHN DRAYTON, OF HOUSTON, TEXAS. I

DENTAL CASTING RING.

Application filed March 16, 1926. Serial No. 95,082.

This invention relates to a dental casting IT: more particularly relates to an electrical dental casting ring.

It has been customary, in making dental castings or inlays, to form a wax model or pattern conforming to the shape of the tooth cavity to be filled.

After the model is removed from the tooth cavity, it is then embedded in investment material such as plaster of Paris. lVhen the plaster is hardened, the wax model is boiled or burned out by increasing the temperature of the mold. The result of such operations is, that a cavity corresponding to the tooth cavity is formed in the investment material into which gold, porcelain or other material may be poured to form the inlay. The sprue hole leading into the cavity of the investment is generally so small that the liquid materials will not flow into it freely, thus necessitating various means for forcing the same therein. Vacuum pressure, or centrifugal force devices have been used for this purpose.

An object of this invention'is to provide a dental casting device wherein the wax models may be readily burned out'or eliminated.

Another object is to provide .a dental casting device which may be readily adapted for use with any of the devices mentioned above.

Further objects and advantages will hereinafter appear.

An embodiment of the invention is illustrated in the accompanying drawing in which,

Fig. 1 shows a central vertical section of the device. I

Fig. 2, shows the device in interior elevation looking at the side containing the connecting socket.

Fig. 3 shows a horizontal section taken on line 33 of Figure'l.

The device comprises a cylindrical spool 1 having upper and lower flanges 2 and 3 respectively. This spool is preferably formed of metal. The outer periphery of the spool between the upper and lower flanges thereof, serve for the incasement of the refractory core. This core is formed of two segments 4 and 5 and may be made of crystalline or other vitreous materials capable of withstanding a high degree of heat. The segments are each provided with a groove 6 so arranged that when the two segments are united to form the core, a single continuous spiral groove is formed. This groove extends from top to bottom of the core and has a heating resistor unit 7 wound 69 therein. The heating resistor unit passes through a hole 8 1n the segment 4, extending from the bottom of the said segment to the top thereof, and is then wound in a sin gle thread from one end of the core to the other and back to they starting point.

Upon the outside of the refractory segment, another layer of refractory material 9 is placed, while in a plastic condition. This material is preferably alundum cement,

although of course, other-forms of refractory cement could be used.

The thermal'heat inthe core formed by the segments is increased because of the refractory material 9, since the bare resistor cannot lose'its heat by radiation from the outward exposed surface thereof. The material 9 furtherserves to lessen the oxidation of the resistor 7. 1 1

In order to further increase the heat and retain the same in the refractory segments an air space 10 separates the outer wall of the casting ring from the plastic material covering the segments. This arrangement is extremely important, since the extent ofthe 35 terminals 13 and 14 which are embedded in a plastic non-conductor.

The innerwall of the casting ring and a flange 15 located at the bottom thereof, form a hollow cylinder for receiving the in vestment materials.

In operation, a wax model or pattern 16 is suspended within the hollow cylinder and investment material 17 is poured therein so as to surround such wax model or pattern. This investment material is then allowed to harden after which the resistor is gradually heated so that the wax may be first boiled off and then completely burned out. The regulation of the heat of the resistors may be obtained in any well known manner such as, and. including, a rheostat in a circuit comprising the same.

It will thus be seen that the wax is boiled off and burned out in one operation. Also, because of the uniform heat obtainable and the manner in which the device retains such heat in the inner cylinder, the casting. of such materials as porcelain may be readily obtained. There will be no decided chilling of the investment at the time of the casting: operation, thereby eliminating; the tendency ofthe material being cast toshrinl:

a break. Furthermore, because of the even heat obtainable within the investment ma terial, there is less danger of destruction or shrinkage ofthe mold; itself.

Having thus described the invention, the following claims are herewith appended, it being distinctly understood, however, that the same is susceptible of many variations and adaptations within the scope of thesaid claims.

\Vhat I claim is: v

1'. r dental casting ring comprising a cylindrical spool member adapted to receive an investment material, a refractory core formed of two complementary segments arranged upon the outer periphery of said :pool member, each segment being provi ed with grooves so arranged-that a continuous spiral groove extending from the bottom to the top of the core is formed when the said segments are joined,v a second refractory core arranged upon the outside'of said first named core, and: a heating element located between said cores for imparting, heat to the investment material.

2; A dental castingring comprising a cylindrical spoobmember adapted'to receive an investment material, a refractory core formed of two complementary segments and having a continuous spiral groove in its outer surface extending from' the bottom to the top thereof arranged upon the outer periphery of said spool member, a second refractory core arranged upon the outside of said first named core, and an electric resistance unit: arranged in said spiral groove'and located between said cores for imparting'heat to the investment material.

3. A dental casting ring comprising a hollow cylindrical spool member having upper and lower flanges extending outwardly from the outer periphery thereof, a refractory core ha *ing upper and lower flanges extending from the outer periphery thereof arranged upon the outside of said spool member between the upper and lower flanges thereof, a second refractory core arranged upon the outside of said first core and located between the upper and lower tlanges thereof, and a heating element arranged between said cores.

A dental casting ring comprisinga hollow cylindrical spool me nber having,- upper and lower flanges extending radially from the outer surface thereof, a refractory core arranged between said flanges upon the outer surface 0f said spool member having outwardly radially ext-ending; flanges of less length than said first named 'anges, a second refractory core arranged" upon the outer surface-of said first named core between the flanges thereof, and a cylindrical casing encircling saic spool member and bearing against the outer side of the flanges thereof, whereby an space is provided between the outer side of said second named core theinner side of said casing.

5; A dental casting ring comprising a cylindrical spool member adaptedtoreceive an investment material, a refractory core arranged upon the outer periphery of id spool'member, said core being provided with a continuous spiral groove upon its outer surface and a heating elementextending vertically through a passage formed in said core to a point near the top thereof and then being wound in said continuous spiral emove, a second refractory core arrange-l upon said first named core, and means for connecting said heating element with an electric circuit whereby heat may be imparted to said-investment material.

In testimony whereof I aflix my ture.

' TON. 

